1. Field of the Invention
The present disclosure relates to an electro phoretic display device, and more particularly, to an electro phoretic display device capable of minimizing the whole thickness and weight by integrally including a photo-sensing touch panel and minimizing the number of lines such as a signal line.
2. Discussion of the Related Art
An electro phoretic display (EPD) device refers to a type of flat panel display used for an E-book, comprising a pair of indication plates each equipped with a field generating electrode, and a micro capsule disposed between the pair of indication plates, the micro capsule containing electric ink having white and black pigment particles respectively electrified to positive or negative potentials.
The EPD device applies voltage to the two facing electrodes so that a potential difference is caused between opposite ends of the electrodes, accordingly moving the black and white electrified pigment particles respectively to the electrodes having opposite polarities and thereby displaying an image.
Such an EPD device is advantageous because it displays an image naturally as if being printed on paper because it has high reflectivity and contrast ratio while being relatively less subject to a viewing angle. Also, the EPD device is capable of maintaining the image without continuous application of a voltage owing to the bistability of black and white, and therefore power consumption can be reduced. Furthermore, in contrast to an LCD, the EPD device does not need a polarizing plate, an alignment layer, and an LCD and so on, thus being advantageous in terms of price competitiveness.
A display device, including the EPD device, as used for some applications require a touch input to operate the device. Thus, a touch screen panel has been mounted on a display panel.
Generally, the touch screen panel may be divided into a resistance type, a capacitor type, and a photo-sensing type, depending on the operating system. These days, the display device is structured by mounting the touch screen panel on the display panel and accordingly is used as a combined display and input device.
However, when the touch screen panel is applied to the conventional EPD device, some problems are incurred as follows.
The EPD device is structured in such a manner that electric ink is interposed between two substrates having a pixel electrode and a facing electrode of the pixel electrode, respectively, and a voltage difference is generated between the pixel electrode and the facing electrode. Therefore, the EPD device operates as ions in the electric ink are moved to corresponding polarities by the voltage difference.
In order to dedicatedly attach the touch screen panel on the EPD device, the touch screen panel and the EPD device need to be separately formed and attached, thereby increasing the whole thickness and the number of processes.
Furthermore, the overlapped structure of the two panels would deteriorate transmittance as a display device.